1. Field of the Invention
The present invention relates to a damping device, in particular to a damping device for a toilet seat cover with a greatly reduced damping while being lifted up and with a variable optimal damping while being closed down.
2. Description of the Related Art
Damping devices are extensively applied to movable covers that usually require a unidirectional damping force. For example, it is desired that no damping force would be generated during the lifting of a toilet seat cover. In contrast, the damping force would be desired during the closing of the toilet seat cover. The existing damping device generally applies a unidirectional blade to serve as an oil switch and also provides a unidirectional obstruction against the damping oil to achieve the one-way damping efficiency. However, the oil channel is often unable to be entirely closed due to the defective cooperation and functioning of the unidirectional blade and the housing, subject to the manufacturing inaccuracy and deformation, and therefore is not able to produce a desired damping to fit the practical need. Moreover, since the design of the damping device is localized in a certain respect, resulting in deficiencies such as bulky in structure, insufficient strength, switch being dull, or insufficient turning angles.
A damping device is disclosed by the China Patent No. 200620009503.6. Referring to FIGS. 13 and 14, the damping device includes an axle 1′, a housing, a unidirectional member 3′, and damping oil. Wherein, the housing has two obstructing walls integrally and extensively installed on an inner wall toward a center thereon. The axle 1′ is installed within the housing, and an outer wall of the axle 1′ props against two top ends of said obstructing walls. The axle includes two ribs integrally and extensively installed thereon. An unoccupied space inside the sealed housing is filled up by the damping oil. The ribs 11′ form U-shaped slots 12′ in cross-section which are axially disposed along the axle 1′. On two sides of each U-shape slots respectively form a first slot wall 13′ and a second slot wall 14′. Wherein, at least one first gap 15′ is respectively formed on an upper end of the first and the second slot walls 13′, 14′ extending toward the insides thereof. The unidirectional member 3′ is pivotally received in the U-shaped slots 12′ at the ribs 11′ of the axle 1′ so as to freely prop between the inner wall of the housing and the bottom of the U-shaped slots 12′. An interval is defined between the unidirectional member 3′ and the slot walls of the U-shaped slots 12′, so that the unidirectional member 3′ would move along the peripheral direction within the slots 12′. The unidirectional member 3′ includes a first section 31′ that props against the inner wall of the housing, a second section 32′ that is movable set near the first section 13′ of the axle 1′, and a third section 33′ that props against the bottom of the slot. Wherein, the portion between the first and second sections 31′, 32′ and the portion between the second and third sections 32′, 33′ are bent and integrally engaged. Thereby, at least one oil hole 30′ is defined on the second section 32′ or on the engaging portion between the second and the third sections 32′, 33′. Additionally, the oil hole 30′ of the unidirectional 3′ in the U-shaped slots 12′ would be staggered with the gap 15′ of the first slot wall 13′. Thus, this invention utilized the closing of the toile seat cover to achieve a preferable damping efficiency and to solve the problem of the blunt switch of the damping device.
However, in the practical application, an oil channel composed by the gap 15′ of the first slot wall 13′, the oil hole 30′ of the unidirectional member 3′, and the gap of the second slot wall 14′ would impede the fluent travel of the damping oil. Therefore, the lifting of the toilet seat cover would be also affected by a certain degree of damping efficiency. Herein, in order to ensure the smooth travel of the oil while lifting the toile seat cover, a second gap is further defined on the outer portion of the first section 31′, and an indentation 34′ is further embraced between the second and the third sections 32′, 33′. By means of the indentation 34′, the cross-section of the unidirectional member 3′ is larger since the structural strength of the unidirectional member 3′ also has to be reserved, which conduces to a larger U-shaped slot 12′. Wherein, a turning angle of rib 11′ of the axle 1 between the two obstructing walls is directed to a lifting angle of the toilet seat cover. The angle is usually set in the range from 100 to 105 degrees. In view of the restrictive angle, the width of the rib 11′ in cross-section should not be too large, which contradict the fact that the width should be concurrently large enough to satisfy the larger U-shaped slots 12′. For meeting the above requirements, the thickness of the slot walls of the convention structure is reduced, which however decreases the structural strength and seriously affects the using life thereof.